1. Field of the Invention
The present invention relates to a technique of processing an image obtained of a board with parts mounted thereon (hereinafter referred to as “the parts mounted board”) and inspecting the soldered state of parts on a board and the mounted state of parts and electrodes on the board, or in particular to a technique for producing inspection data for this type of inspection.
2. Description of the Prior Art
In carrying out this type of inspection automatically, it is necessary to set various inspection data (this setting process is hereinafter referred to as “the teaching”) for each part on the board, including the set data for the inspection window corresponding to the particular part (including the data indicating the set position and the size of the window), a parameter required to extract an image pattern in the inspection window (binary threshold value, etc.), a program for processing the extracted image pattern (hereinafter referred to as “the inspection program”) and a criterion for determining whether the result of the processes is proper or not.
Generally, an inspection window for a plurality of portions including a land, a part and an electrode is set for each type of component part. Also, the parameter, the inspection program and the criterion described above are set for each window (the data and the program set for each of these windows is hereinafter referred to as “the inspection reference data”). Further, the inspection data for each part is made into a file and registered in a memory of the board inspection apparatus (this file is hereinafter referred to as “the inspection data file”)
In the conventional board inspection apparatus, a parts library with inspection data registered therein for each part type is registered. The user executes for each part the process of designating the mounting position of the part on a model board image in a satisfactory mounting state, and attaching at a designated position the inspection data read from the parts library. In this way, an inspection data file can be efficiently produced.
Further, the teaching can be automated using the board design data such as the CAD data. In this case, the control unit of the inspection apparatus extracts the mounting position and the item number data of the particular part from the design data, reads the inspection data corresponding to the item number data from the parts library and sets the inspection data at the mounting position (Japanese Unexamined Patent Publication No. 5-35849).
The lands on the board are required to be designed taking into consideration various factors including the mounting condition of the electrodes and the heat radiation of the board in operation. The land size, therefore, is different for a different design rule. Some makers have no unified design rule and have different land sizes for different boards. Even those makers having a unified design rule sometimes set a plurality of land sizes based on old and new rules, or set different land sizes for different board sizes. Further, manufacturers fabricating a board on consignment for a plurality of makers are required to produce and inspect boards having various sizes of lands in view of the fact that the design rule varies from one maker to another.
The parts library described above is produced using a board image based on a predetermined design rule. In the case where a board changed in land size due to a different design rule is inspected, however, the situation may not be met by the inspection data in this parts library. In such a case, according to the prior art, the inspection windows are displayed in superposed relation on the image of a reference board after producing an inspection data file, and the user is caused to correct the position and size of the window manually. This correcting job consumes a great amount of time (the correction of a single board may consume about one half of a day). Thus, the burden on the user increases, and the inspection cannot be started early.